1. Field of the Invention
The present invention relates to a driving device and a camera that drive a plurality of mechanisms using a plurality of motors as driving sources.
2. Description of the Related Art
Some single-lens reflex cameras use motors as driving sources to drive a mirror driving system, a shutter charge driving system, a film winding or rewinding driving system, an electronic flash popping-up or -down driving system, and the like.
For example, a camera proposed in Japanese Laid-Open Patent Publication (Kokai) No. 3-75626 incorporates two motors disposed such that the first motor is rotated in one direction to wind a film and in the other direction to drive a mirror and a shutter, whereas the second motor is rotated in one direction to rewind the film and in the other direction to drive an electronic flash.
Further, various cameras have been proposed which use a single motor as a driving source to feed the film, charge the shutter, drive the mirror, and so on.
For example, a camera proposed by Japanese Laid-Open Patent Publication (Kokai) No. 1-202731 employs a preliminary winding system wherein the camera main body incorporates a single motor disposed such that when a user opens a rear cover, charges a film cartridge into the camera, and then closes the rear cover, a full-amount winding spool winds a film in the film cartridge to set the camera into a photographing standby state. Thereafter, in photographing, this motor is used to rewind the film, charge the shutter, and drive the mirror through switching of a planetary clutch.
In this camera, when the motor is rotated in one direction, the planetary clutch is connected to a first transmission system on a film winding side, and as the motor continues to rotate in the same direction, the film is wound. Once the winding operation is completed, the motor is rotated in the other direction to connect the planetary clutch to a second transmission system. When the motor is rotated in the other direction with the planetary clutch connected to the second transmission system, a series of photographing operations including film rewinding, mirror pop-up and -down, and shutter charging are performed while a rotary cam member makes a turn.
Further, a motor driving device proposed in Japanese Laid-Open Patent Publication (Kokai) No. 1-287648 drives a plurality of planetary clutch mechanisms (planetary clutches) using a single motor. The motor is rotated in one direction to cause a first planetary clutch to perform a switching operation to select a driving system to which power is transmitted when the motor rotates in the other direction. Once the driving system is selected in this manner, the motor is rotated in the other direction to transmit motor power to the selected driving system.
Moreover, a camera has been proposed in Japanese Laid-Open Patent Publication (Kokai) No. 8-328094, in which a plurality of planetary clutch mechanisms (planetary clutches) are driven by a single motor. The motor is rotated in one direction to perform mirror driving and shutter charge driving and perform a switching operation to select one planetary clutch for power transmission, and is rotated in the other direction to transmit its driving power to one of driving mechanisms for film winding, film rewinding, and electronic flash pop-up to prepare for photographing, which is the destination of power transmission from the selected planetary clutch.
Further, a camera proposed in Japanese Laid-Open Patent Publication (Kokai) No. 7-270877 uses a motor that drives a taking lens barrel to distribute power to other motors.
Moreover, a camera proposed in Japanese Laid-Open Patent Publication (Kokai) No. 61-269129 includes a film winding mechanism having two types of gear ratios for high-speed winding and low-speed winding, which are switched depending on load, power supply, or the like or to switch from the low-speed winding to the high-speed-winding for preliminary winding.
However, in the camera proposed in Japanese Laid-Open Patent Publication (Kokai) No. 3-75626, the two motors each carry our the film driving, mirror driving, and shutter charge driving, but since these driving systems undergo relatively heavy driving loads, large-sized motors of high power are employed for these motors if a camera having a high continuous photographing speed is to be provided. Thus, the camera will be expensive and large in size.
Further, the camera proposed in Japanese Laid-Open Patent Publication (Kokai) No. 2-202731 uses only one motor, thus making it possible to reduce its own size.
The use of the preliminary film winding system, however, requires a rear cover interlocking mechanism and the like, thereby hindering the entire system or layout from being designed freely.
Moreover, the motor driving device proposed in Japanese Laid-Open Patent Publication (Kokai) No. 1-287648 also uses only one motor, but it requires as many planetary clutches as the number of the driving systems to which power is transmitted, thus requiring a large-sized mechanism. Further, since one operation is completed by a set of rotations of the motor in one and the other directions, a complicated sequence is required for a series of plural operations. If this motor driving device is applied to a camera, the continuous photographing speed will be low.
Furthermore, the camera proposed in Japanese Laid-Open Patent Publication (Kokai) No. 8-328094 uses only one motor, but the cam member for causing the series of photographing operations including mirror driving and shutter charge driving to be performed during one rotation thereof is provided with phases for phase indexing that allow the electronic flash to pop up after photographing operation has been completed. Consequently, this camera is not optimal for increasing the continuous photographing speed.
Further, the camera proposed in Japanese Laid-Open Patent Publication (Kokai) No. 7-270877 determines driving force transmitting paths for the motors other than the one for driving the lens barrel, based on a position in which the lens barrel is stopped, thereby hindering the driving force transmitting paths used from being selected freely.
With respect to the film winding operation, which significantly affects the speed of the continuous photographing operation, the load required for film winding varies with the type of the commercially available film. Further, at low temperature, the film winding load increases, so that the gear ratio of the film winding mechanism must be set to such a gear ratio as can deal with a high load of about 800g. Consequently, the film winding speed necessarily decreases in normal photographing.
Furthermore, in all the above conventional constructions, the gear ratio of the film winding mechanism is set to a single gear ratio, thus limiting an increase in the continuous photographing speed.
To cope with this problem, the camera proposed in Japanese Laid-open Patent Publication (Kokai) No. 61-269129 is provided with a winding mechanism having two gear ratios for high and low speeds. However, it requires an exclusive motor for winding the film. Further, other relatively large-sized motors are required for driving mechanisms for mirror driving, shutter charging, film rewinding, and others which deal with relatively heavy loads. Thus, the camera has to be large in size.
Further, in a power distribution mechanism using a plurality of planetary mechanisms driven by a single motor as a driving source, if the motor is stopped or suddenly decelerated upon a sudden change in the load upon a planetary mechanism which is being revolved while transmitting power by the motor rotating in one direction, the other planetary mechanism(s), which is(are) then held out of its(their) engaged or meshing position(s) through a revolution-blocking member or the like, can make a revolving motion(revolving motions)in a direction in which it(they) is(are) caused to revolve when the motor rotates in the other direction, resulting in a behavior which is different from a proper behavior. For example, in the camera proposed in Japanese Laid-Open Patent Publication (Kokai) No. 8-328094, if such an abnormal operation occurs that the film becomes taut or tensioned during rewinding, the other planetary clutch than the one that is transmitting power for the film rewinding is caused to rebound and revolve in the direction of the mirror being driven and the shutter being charged, which is opposite to the direction in which the other planetary clutch is blocked from revolving, so that it is brought into an engaged position.
It is a first object of the present invention to provide a driving device and a camera which are compact in size and inexpensive even with the use of two motors, which allow relevant mechanisms to be laid out freely to thereby simplify motor controlling sequences, and which ensure positive power transmission operations even upon abnormal load change during film rewinding.
To attain the above object, in a first aspect of the present invention, there is provided a driving device provided in an apparatus for driving a plurality of driving systems by means of motors as driving sources, comprising a first motor, first and second planetary mechanisms responsive to rotation of the first motor in a desired direction, for revolving in a direction corresponding to the desired direction to transmit a driving force of the first motor, a first driving system disposed for engagement with the first planetary mechanism to have the driving force of the first motor transmitted thereto via the first planetary mechanism when the first motor rotates in a first direction, a second driving system disposed for engagement with the first planetary mechanism to have the driving force of the first motor transmitted thereto via the first planetary mechanism when the first motor rotates in a second direction, a third driving system disposed for engagement with the second planetary mechanism to have the driving force of the first motor transmitted thereto via the second planetary mechanism when the first motor rotates in the first direction, and a switching mechanism responsive to rotation of the first motor in the desired direction, for switching a transmission path for the driving force of the first motor by inhibiting one of the first and second planetary mechanisms from revolving, and for causing the other of the first and second planetary mechanisms to transmit the driving force of the first motor through a transmission path selected by the switching, wherein the first and second planetary mechanisms have first and second restraint members, respectively, for restraining the first and second planetary mechanisms from revolving simultaneously by inhibiting concurrence of engagement of the first planetary mechanism with the second driving system and engagement of the second planetary mechanism with the third driving system.
To attain the above object, in a second aspect of the present invention, there is provided a camera having a plurality of driving systems driven by means of motors as driving sources, comprising a first motor, first and second planetary mechanisms responsive to rotation of the first motor in a desired direction, for revolving in a direction corresponding to the desired direction to transmit a driving force of the first motor, a first driving system disposed for engagement with the first planetary mechanism to have the driving force of the first motor transmitted thereto via the first planetary mechanism when the first motor rotates in a first direction, a second driving system disposed for engagement with the first planetary mechanism to have the driving force of the first motor transmitted thereto via the first planetary mechanism when the first motor rotates in a second direction, a third driving system disposed for engagement with the second planetary mechanism to have the driving force of the first motor transmitted thereto via the second planetary mechanism when the first motor rotates in the first direction, and a switching mechanism responsive to rotation of the first motor in the desired direction, for switching a transmission path for the driving force of the first motor by inhibiting one of the first and second planetary mechanisms from revolving, and for causing the other of the first and second planetary mechanisms to transmit the driving force of the first motor through a transmission path selected by the switching, wherein the first and second planetary mechanisms have first and second restraint members, respectively, for restraining the first and second planetary mechanisms from revolving simultaneously by inhibiting concurrence of engagement of the first planetary mechanism with the second driving system and engagement of the second planetary mechanism with the third driving system.
Preferably, a fourth driving system is disposed to have the driving force of the first motor transmitted thereto via the second planetary mechanism when the first motor rotates in the second direction.
Also preferably, an actuator is provided for driving the switching mechanism to cause the switching mechanism to switch the transmission path for the driving force of the first motor.
More preferably, the actuator comprises a second motor having a smaller output than the first motor, the driving device including a third planetary mechanism for transmitting a driving force of the second motor, and wherein the switching mechanism is actuated by the driving force of the second motor transmitted through the third planetary mechanism.
Further preferably, a fifth driving system is disposed to have the driving force of the second motor transmitted thereto via the third planetary mechanism when the second motor rotates in the second direction.
Preferably, the second driving system and the third driving system cause operations of a device that performs a predetermined kind of operation, in opposite directions to each other.
In a preferred form of the present invention, the switching mechanism selectively switches between a state in which the first planetary mechanism is permitted to be drivingly connected to the first driving system and the second driving system while the second planetary mechanism is inhibited from being connected to the third driving system and the fourth driving system, a state in which the first planetary mechanism is permitted to be drivingly connected to the first driving system and the second planetary mechanism is permitted to be drivingly connected to the fourth driving system while the first planetary mechanism is inhibited from being connected to the second driving system and the second planetary mechanism is inhibited from being connected to the third driving system, and a state in which the second planetary mechanism is permitted to be drivingly connected to the third driving system while the first planetary mechanism is inhibited from being connected to the first driving system.
Preferably, a sun gear member is disposed to be driven by the first motor, and the first and second planetary mechanisms are disposed to revolve around the sun gear member independently of each other, the first and second planetary mechanisms having respective revolving shafts having bearing portions and being concentrically arranged, the first and second restraint members being provided on the bearing portions.
In a preferred form of the camera according to the present invention, there are provided a mirror disposed to advance into and recede from a photographic optical path, and a shutter, and the first driving system comprises a driving system for driving the mirror, and for driving charging of the shutter, the second and fourth driving systems comprise film winding driving systems that wind a film at different speeds from each other, and the third driving system comprises a film rewinding driving system.
With the arrangement of the present invention, the first motor drives all the driving systems that cause execution of operations such as the photographing and film feeding operations for the camera, which require relatively high driving loads, and the second motor drives the switching mechanism and driving systems that cause execution of operations other than the photographing and film feeding operations, which require relatively light driving loads. As a result, the second motor can be selected to have a lower output (and a smaller size) than the first motor. Besides, two motors are used, so that the mechanisms can be laid out more freely and a relatively smaller number of, planetary mechanisms are required than when only one motor is used. As a result, the entire size of the apparatus or camera and its costs can be reduced.
Furthermore, since one apparatus or camera operation can be performed by rotation of the motor in only one direction, the motor controlling sequence can be simplified compared to a case where rotations in both directions are combined together to perform one operation.
Further, the second and fourth driving systems can be operated to perform the same apparatus operation (for example, the film winding operation for the camera) at different speeds, optimal and efficient driving operations can be performed depending on the state of the power supply, driving loads, or the like. In particular, in the camera, the continues photographing frame speed can be selected to a desired speed. In any case, the photographing operation can be performed by rotating only one motor in the normal direction alone or in the reverse direction alone.
Furthermore, even if the driving device or the camera is configured such that the second and third driving systems cause operations of the same device that performs a predetermined kind of operation, in opposite directions to each other (for the film winding operation and the film rewinding operation of the camera, respectively), since concurrence of engagement of the first planetary mechanism with the second driving system and engagement of the second planetary mechanism with the third driving system is inhibited, a positive and reliable operation of the driving device or the camera can be ensured.